SOLUTION: How many liters of pure acid must be mixed with 20 liters of a 15% acid solution to get 20% mixture?

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Question 125444: How many liters of pure acid must be mixed with 20 liters of a 15% acid solution to get 20% mixture?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
How many liters of pure acid must be mixed with 20 liters of a 15% acid solution to get 20% mixture?
:
Let x = amt of pure acid required
:
This is to be mixed with 20 liters, therefore:
The amt of the final mixture will = (x+20)
:
Pure acid will be 1.0x
:
.15(20) + 1.0x = .20(x+ 20)
:
3 + 1x + .20x + 4
:
1x - .2x = 4 - 3
:
.8x = 1
x = 1%2F.8
x = 1.25 liters of pure acid to produce a 20% mixture
:
:
Check
.15(20) + 1.25 = .20(21.25)
3 + 1.25 = 4.25; confirms our solution